1. Field of the Invention
The present invention relates to a sensitizing dye solution, a working electrode for a dye-sensitized solar cell prepared using the sensitizing dye solution, and a dye-sensitized solar cell including the working electrode.
2. Description of the Related Art
In recent years, fossil fuels have been depleted and environmental pollution has been issued as a serious problem. Under such circumstances, next generation energy development has gained increasing importance. Particularly, solar cells for directly converting solar energy emitted from sunlight into electrical energy produce less pollution, utilize the inexhaustible energy resource, and can be used semi-permanently. Due to these advantages, solar cells are expected as future energy sources.
Solar cells are broadly classified into inorganic solar cells, dye-sensitized solar cells, and organic solar cells by the kind of material that they employ. Most inorganic solar cells use single crystalline silicon. Single crystal silicon solar cells can be advantageously fabricated in the form of thin films but suffer from the problems of high cost and poor stability.
Dye-sensitized solar cells are photoelectrochemical solar cells and a prototype thereof was first presented by Grätzel et al., Switzerland, in 1991. Dye-sensitized solar cells require no junction at all, unlike p-n junction solar cells as general types of solar cells.
Such a dye-sensitized solar cell includes a working electrode covered with porous TiO2, a counter electrode covered with platinum, and an electrolyte located between the two electrodes and through which ions migrate. A sensitizing dye capable of absorbing visible light is adsorbed onto the working electrode to create electron-hole pairs.
The dye excites electrons, the excited electrons reach the counter electrode through the TiO2 particles of the working electrode, and redox reactions proceed in the electrolyte to operate the dye-sensitized solar cell.
Dye-sensitized solar cells are fabricated in a simple and economical manner and have high energy conversion efficiency compared to silicon solar cells. Due to these advantages, dye-sensitized solar cells have attracted much attention as promising next generation replacements for existing silicon solar cells.
The energy conversion efficiency of dye-sensitized solar cells using liquid electrolytes was reported to be about 12% in 2011. Dyes creating electron-hole pairs need to be adsorbed. However, this process is very time consuming and is thus an obstacle to the commercialization of dye-sensitized solar cells.
There is thus a need for a working electrode in which a dye is fast adsorbed and does not undergo desorption despite the shortened adsorption time to guarantee long-term stability and high efficiency of a solar cell, and a dye-sensitized solar cell using the working electrode.